Generators have been widely used in a variety of applications including aircraft, automobiles and turbines. Generators typically include a stator and a rotor that work together to produce electricity. Wind turbines have received increased attention recently as an environmentally safe alternative energy source. Wind turbines convert the kinetic energy of the wind into mechanical power and then the mechanical power drives the generator to produce electricity.
Offshore wind turbines typically have ratings of 3MW and higher, necessitated by the economics of wind energy production. Also offshore turbines employ a direct drive generator to improve reliability, unlike most land based utility scale wind turbines that utilize a geared generator. These ratings and the fact that the generator is directly driven manifests into a very large size and weight. A machine greater than 4 m in diameter is difficult and costly to transport by conventional means and necessitates segmentation.
Alternatively, a 3MW machine could be made within a 4 m diameter limit by making it axially longer or utilizing a double-sided configuration. Both of these options present challenges. An axially longer machine weighs significantly more than a shorter length larger diameter machine whereas a double-sided configuration presents significant manufacturing complexity. While the segmented stator structures facilitate cost and transport, particularly when designed to accommodate conventional rail or road shipping constraints, they are difficult to manufacture and assemble at site.
For these and other reasons, there is a need for the present invention.